Method and force-limiting handle mechanism for a surgical instrument

Abstract

A safety handle assembly for use with a surgical instrument having an operative distal end portion is disclosed. The handle assembly includes a handle housing and a drive element movably mounted within the handle housing and connected to an associated operative distal end portion. A drive assembly is positioned within the handle housing and is engageable with the drive element to move the drive element within the handle housing. An actuator is movably mounted on the handle housing and an adjustable force-limiting mechanism is interposed between the drive assembly and the actuator. A force-limiting mechanism releasably connects the actuator to the drive assembly. The force-limiting mechanism is adjustable to preset the force at which the actuator separates or breaks away from the drive assembly.

The invention claimed is: 
     
       1. A handle assembly for use with a surgical instrument having an operative distal end portion comprising:
 a handle housing; 
 a drive element movably mounted within the handle housing and connected to an operative distal end portion for performing surgery; 
 an actuator movably mounted on the handle housing; and 
 a force-limiting mechanism disposed between the drive element and the actuator, the force-limiting mechanism having a breakaway force, the force-limiting mechanism including:
 a carriage in mechanical cooperation with the actuator; 
 a pawl pivotably connected to the carriage; 
 a plunger slidably connected to the actuator; 
 wherein the carriage includes an angled surface for engaging at least a portion of the plunger; 
 
 the force-limiting mechanism being attached to the actuator so that the force-limiting mechanism moves with the actuator when the force applied to the actuator is less than the breakaway force and so that the force-limiting mechanism pivots with respect to the actuator when the force applied to the actuator meets the breakaway force, the force-limiting mechanism applying a drive force to the drive element when the force applied to the actuator is less than the breakaway force. 
 
     
     
       2. The handle assembly as recited in  claim 1 , wherein the force-limiting mechanism includes a lower carrier. 
     
     
       3. The handle assembly as recited in  claim 2 , wherein the force-limiting mechanism includes a connecting rod connected to the actuator and releasably connected to the lower carrier. 
     
     
       4. The handle assembly as recited in  claim 3 , wherein the connecting rod is slidably disposed in the actuator and a spring is positioned between the actuator and the connecting rod. 
     
     
       5. The handle assembly as recited in  claim 4 , wherein the lower carrier is pivotably connected to the actuator. 
     
     
       6. The handle assembly as recited in  claim 5 , wherein the lower carrier is pivotably connected to an upper carrier, the upper carrier being pivotably connected to the connecting rod. 
     
     
       7. The handle assembly as recited in  claim 2 , wherein the drive element comprises a rack having at least one tooth and further comprising a pawl pivotably connected to the force-limiting mechanism for engagement with the rack. 
     
     
       8. The handle assembly as recited in  claim 1 , wherein the plunger is slidably disposed at least partially within the actuator. 
     
     
       9. The handle assembly as recited in  claim 8 , wherein at least one spring is disposed between the plunger and the actuator. 
     
     
       10. The handle assembly as recited in  claim 1 , wherein the plunger includes an angled face for engaging the angled surface, the angled surface and angled face being arranged so that the carriage is able to depress the plunger. 
     
     
       11. The handle assembly as recited in  claim 10 , wherein the plunger is biased toward the carriage with a predetermined amount of force.